<!doctype html>
<html>
    <head>
        <title></title>
        <meta charset="utf-8" />
        <style>
         div {
             width: 200px;
             height: 30px;
             padding: 20px;
             border: 5px solid #f00;
             margin: 10px;
             color: #ffffff;
             background-color: #000000;
         }

         /* div + div {
            border-width: 10px 5px;
            border-color: #0f0;
            }

            div + div + div {
            border-width: 0 5px 5px;
            border-color: #00f;
            } */
        </style>
    </head>
    <body>
        <div>我是第一个div标签哦</div>
        <div>那我就是第二个div标签啦</div>
        <div>显然，我就是第三个div标签</div>
    </body>
</html>
